From what I hear a worked Holden 5 litre outperforms the 350 C.I. motor as the 5 litre has better bottom end performance whereas the Chev is more of a top end motor and lacks a little down low,my brothers mates father was really into the American cars and reckoned the 327 motor was more ballsy.
I could always remember on the Fastlane website when someone imported a 350 powered Chev (whole car),they were disappointed with its performance and someone mentioned maybe you were expecting too much from a Chev.